KVM管理虚拟机：常用命令

电玩女神 2022-01-28 05:11 931阅读 0赞

# 安装kvm #

文档参考：  
CentOS7 ：[http://www.linux-kvm.org/page/HOWTO\#RHEL.2FCentOS\_7][http_www.linux-kvm.org_page_HOWTO_RHEL.2FCentOS_7]  
CentOS6 ：[https://wiki.centos.org/zh/HowTos/KVM][https_wiki.centos.org_zh_HowTos_KVM] \--> 白皮书: [第一册][Link 1]， [第二册][Link 2]

*  1.a,创建虚拟机
 *  1.b,运行/停止虚拟机
 *  1.c,查看虚拟机

--------------------

*  虚拟机配置调整：内存，磁盘，cpu数
 *  虚拟机的两大主要文件：image, xml文件

##  1,  image路径： 
    root@controller:/var/lib/libvirt/images# ls
    cent7-clone.qcow2  cent7.qcow2  centos7.0.qcow2
     
     ##  2,  虚拟机xml配置文件路径： 
    root@controller:/etc/libvirt/qemu# ls
    cent7-clone.xml  cent7.xml  centos7.0.xml  networks

# 1, 虚拟机：生命周期管理 #

*  a， 创建虚拟机 (virt-install)

#内存：1G,   cup: 2,   硬盘:30G
    ###执行命令后，满足条件就会弹出centos的安装界面
     virt-install \
     --name c6 \
     --ram=1024 \
     --vcpus=2 \
     --network=bridge:br0 \
     --disk path=/var/lib/libvirt/images/c6.img,size=30  \
     --cdrom /CentOS-6.10-x86_64-minimal.iso

*  b,查看/运行/停止虚拟机 (virsh list/ start/ shutdown,destroy)

root@controller:/home/wang# virsh list 
     Id    Name                           State
    ----------------------------------------------------
     6     centos7.0                      running
     9     cent7                          running
    
    root@controller:~/openstack# virsh dominfo cent7
    Id:             20
    Name:           cent7
    UUID:           a566d8e4-ec6f-42d7-9d31-8d0d3ce5f09a
    OS Type:        hvm
    State:          running
    CPU(s):         2
    CPU time:       197.0s
    Max memory:     2097152 KiB
    Used memory:    1048576 KiB
    Persistent:     yes
    Autostart:      disable
    Managed save:   no
    Security model: apparmor
    Security DOI:   0
    Security label: libvirt-a566d8e4-ec6f-42d7-9d31-8d0d3ce5f09a (enforcing)
    
    ################# autostart, start,  shutdown, reboot  //pause,  resume
    root@controller:/etc/network# virsh  shutdown cent7
    Domain cent7 is being shutdown
    
    root@controller:/etc/network# virsh  list --all
     Id    Name                           State
    ----------------------------------------------------
     6     centos7.0                      running
     -     cent7                          shut off

*  3, 删除虚拟机

root@controller:/ # cat /usr/local/bin/kvm-delete.sh
    read -p '输入(要删除的虚拟机)：'  name
    echo "....going to delete ..$name"
    
    #1,destroy
    virsh destroy $name
    
    #2,undefine
    virsh undefine $name
    
    #3,del image
    rm -f /var/lib/libvirt/images/$name.qcow2
    echo "delete kvm $name --> ok...."

# 2, kvm登录虚拟机 #

*  virsh console xx

#virt-viewer -c qemu:///system VMachinename
    virt-viewer  cent7

# 3, 虚拟机内存调整 #

## setmaxmem                      change maximum memory limit
    ## setmem                            change memory allocation
    #虚拟机开机后，动态内存扩展(加上--config表示写入到配置文件，永久生效)
    virsh setmaxmem centos7  9GB --config
    virsh  setmem centos7    8GB  --config
    
    ## setvcpus                       change number of virtual CPUs
    ## setvcpu                        attach/detach vcpu or groups of threads

# 4, 复制/克隆虚拟机 #

virt-clone命令： 需要关闭虚拟机再操作

root@controller:~/openstack# virt-clone -o cent7 -n cent7_2 --auto-clone
    正在分配 'cent7_2.qcow2'                                                                                           | 5.0 GB  00:00:23     
    
    成功克隆 'cent7_2'。
    root@controller:~/openstack# virsh list --all
     Id    Name                           State
    ----------------------------------------------------
     18    stack                          running
     -     cent7                          shut off
     -     cent7_2                        shut off
    
    root@controller:~/openstack# ls /var/lib/libvirt/images/
    cent7_2.qcow2  cent7.qcow2  centos7.0.qcow2  stack.qcow2
    
    root@controller:~/openstack# ls /etc/libvirt/qemu
    cent7_2.xml  cent7.xml  networks  stack.xml

若没有关闭虚拟机来克隆就会报以下错误：

root@controller:~# virsh list
     Id    Name                           State
    ----------------------------------------------------
     11    centos7.0                      running
     12    cent7                          paused
    
    root@controller:~# virt-clone -o cent7 --auto-clone
    WARNING  设置图形设备端口为自动端口，以避免相互冲突。
    ERROR    Couldn't create storage volume 'cent7-clone.qcow2': 'internal error: Child process (/usr/bin/qemu-img convert -f qcow2 -O qcow2 -o compat=1.1,lazy_refcounts /var/lib/libvirt/images/cent7.qcow2 /var/lib/libvirt/images/cent7-clone.qcow2) unexpected exit status 1: qemu-img: Could not open '/var/lib/libvirt/images/cent7.qcow2': Failed to get shared "write" lock
    Is another process using the image?

# 5,虚拟机重命名 #

把上面的cent7-clone 这个刚克隆的虚拟机重命名(先停止虚拟机）–> cent7\_2

root@controller:~# virt-clone -o cent7 --auto-clone
    正在分配 'cent7-clone.qcow2'                                                                                       |  40 GB  00:00:47     
    成功克隆 'cent7-clone'。
    
    #启动克隆好的虚拟机
    root@controller:~# virsh  start cent7
    Domain cent7 started
    root@controller:~# virsh  start cent7-clone
    Domain cent7-clone started
    
    root@controller:~# virsh list
     Id    Name                           State
    ----------------------------------------------------
     11    centos7.0                      running
     13    cent7                          running
     14    cent7-clone                    running
     
    # 1, xml修改
    root@controller:~# virsh dumpxml cent7-clone > /etc/libvirt/qemu/cent7_2.xml
    root@controller:/etc/libvirt/qemu# ls
    cent7_2.xml  cent7-clone.xml  cent7.xml    networks
    ####修改旧的名字， 为新的名字
    root@controller:/etc/libvirt/qemu# grep cent7-clone cent7_2.xml 
      <name>cent7-clone</name>
          <source file='/var/lib/libvirt/images/cent7-clone.qcow2'/>
    root@controller:/etc/libvirt/qemu# sed -i s/cent7-clone/cent7_2/g cent7_2.xml 
    
    # 2, image文件重命名
    root@controller:/var/lib/libvirt/images# ls
    cent7-clone.qcow2  cent7.qcow2 
    root@controller:/var/lib/libvirt/images# mv cent7-clone.qcow2 cent7_2.qcow2
    
    # 3,  废弃旧的虚拟机，使用新的虚拟机
    root@controller:~# virsh list
     Id    Name                           State
    ----------------------------------------------------
     13    cent7                          running
     14    cent7-clone                    running
    
    root@controller:~# virsh  shutdown  cent7-clone
    Domain cent7-clone is being shutdown
    root@controller:/etc/libvirt/qemu# virsh undefine cent7-clone  
    Domain cent7-clone has been undefined
    root@controller:/etc/network# ls /etc/libvirt/qemu/
    cent7_2.xml    cent7.xml      centos7.0.xml  networks/  
    
    root@controller:/etc/libvirt/qemu# virsh list --all
     Id    Name                           State
    ----------------------------------------------------
     13    cent7                          running
    
    root@controller:/etc/libvirt/qemu# virsh define cent7_2.xml
    Domain cent7_2 defined from cent7_2.xml
    root@controller:/etc/libvirt/qemu# virsh start cent7_2
    viDomain cent7_2 started
    
    root@controller:/etc/libvirt/qemu# virsh list
     Id    Name                           State
    ----------------------------------------------------
     13    cent7                          running
     15    cent7_2                        running

# 6, kvm导出virtualbox/vmware虚拟机 #

*  把kvm的虚拟机磁盘文件导出为vdi,vmdk即可在virtualbox或vmware中使用此虚拟机

sudo qemu-img convert /var/lib/libvirt/images/win7.qcow2 -O vdi ./win7.vdi

[http_www.linux-kvm.org_page_HOWTO_RHEL.2FCentOS_7]: http://www.linux-kvm.org/page/HOWTO#RHEL.2FCentOS_7
[https_wiki.centos.org_zh_HowTos_KVM]: https://wiki.centos.org/zh/HowTos/KVM
[Link 1]: http://linux.dell.com/files/whitepapers/KVM_Virtualization_in_RHEL_6_made_easy.pdf
[Link 2]: http://linux.dell.com/files/whitepapers/KVM_Virtualization_in_RHEL_6_Made_Easy_Part2.pdf